Members of this family have swollen joints where each leaf is attached, often giving the stem a zig-zag appearance. The family name meaning "many knees" or "many joints" and the common name "knotweed", refer to this characteristic. The flowers are made up of sepals, without petals, which are often colored. The leaves are lanceolate and the plant can spread by runners.

Smartweed has spread extensively in this wetland, covering large areas of open water and forming a tangled mass of stems in the water. Much of it has dried out over summer or been defoliated by caterpillars (probably moth caterpillars), but it returns again.

Although smartweed can be a nuisance in covering open water, it provides cover and food for wildlife. Red-winged blackbirds can be seen foraging on a mat of smartweed formed above the water. Raccoons and muskrats are known to eat smartweed stems and leaves, while the seeds are eaten by mice and many species of birds. Smartweed is often one of the first invaders of vacated, low-lying, wet farmland since it is avoided by livestock because of high concentrations of calcium oxalate in the leaves.

Smartweeds can most clearly be identified by the ocrea, a sheath which forms around the joints on the stem. The following martweed species are found in these wetlands:

P. caespitosum or long-bristled smartweed has long ocreae with bristles which are about as long as the sheath itself. It is an invasive weed and is classified as a category 2 noxious weed in Tennessee. It is also known as Japanese knotweed or oriental lady's thumb. The flowers are pink to white; the leaves are red early in the season and become green.

P. pensylvanicum or Pennsylvania smartweed is a FACW plant. The ocreae are without bristles (although they may be ragged), and the joints are a reddish color. Flowers are pink or white.

P. persicaria or spotted lady's thumb is the most prevalent smartweed. It has a purplish "thumbprint" on many of its leaves.